Question

To illustrate the effects of driving under the influence (DUI) of alcohol, a police officer brought a DUI simulator to a local high school. Student reaction time in an emergency was measured with unimpaired vision and also while wearing a pair of special goggles to simulate the effects of alcohol on vision. For a random sample of nine teenagers, the time (in seconds) required to bring the vehicle to a stop from a speed of 60 miles per hour was recorded. Construct a 95% confidence interval for the mean difference in stopping time for impaired students versus normal students.

Student:	1	2	3	4	5	6	7	8	9
Normal:	4.47	4.24	4.58	4.65	4.31	4.80	4.55	5.00	4.79
Impaired:	5.77	5.67	5.51	5.32	5.83	5.49	5.23	5.61	5.63

Conditions:
In Minitab Express, enter the given data in two separate columns, use DATA -> Formula to calculate the differences d_i as d = Impaired - Normal, and perform a normality test on the resulting differences.

a) The P-value from the Anderson-Darling test of normality is ____. (Do not round.)

b) The necessary conditions for constructing a confidence interval for μ_d ____(are / are not) satisfied.

c) The appropriate critical value for this confidence interval is t_α/2 = _______. (Report critical values as they appear in the table.)

Confidence Interval:
d) We are 95% confident that impaired students take between______ (lower) and _______ (upper) seconds longer to come to a complete stop than normal. Report your answers rounded to 3 decimal places, where applicable.

Answer 1

a) The P-value from the Anderson-Darling test of normality is 0.063. (Do not round.)

b) The necessary conditions for constructing a confidence interval for μd ____(are) satisfied.

c) The appropriate critical value for this confidence interval is tα/2 = 2.306. (Report critical values as they appear in the table.)

Confidence Interval:
d) We are 95% confident that impaired students take between 0.688 (lower) and 1.238 (upper) seconds longer to come to a complete stop than normal. Report your answers rounded to 3 decimal places, where applicable.